Materials Characterization Paper 

In Support of the 

Final Rulemaking: 

Identification of Nonhazardous Secondary Materials That Are Solid Waste 

Coal Refuse 

February 3, 2011 

================================================================= 

1. Definition of Coal Refuse 

This paper focuses on coal refuse that is a by-product of coal mining (mining rejects).1

 Coal 

refuse is generally defined by a minimum ash content combined with a maximum heating value, 

measured on a dry basis (ARIPPA, p. 1 and EPA 2002, p. 2-2). Coal refuse mining rejects are a 

low BTU-value material generated by the coal mining process. The material consists primarily 

of non-combustible rock, with some attached carbon material that could not be effectively 

separated due to its small size. Large volumes of these materials were accumulated at mining 

sites from the time mining first began in the Appalachians through the late 1970s. Beginning in 

the late 1970s, laws were enacted that, for the first time, required stabilization and reclamation of 

mining sites, including coal refuse disposal piles and fills (ARIPPA, p.1). Current mining 

operations continue to generate the material, though likely at lower rates than in previous 

decades (Neufeld p. 1). Mining rejects are referred to by various names, including: “gob” 

(garbage of bituminous) or “boney” in the bituminous coal mining regions of western 

Pennsylvania, West Virginia and elsewhere; and “culm” in the eastern Pennsylvania anthracite 

region. Coal refuse piles also may be referred to as slate dumps (Energy Justice 2007, p.1; 

WPCAMR 2001, p.2; NRC 2006, p.16). 

2. Annual Quantities of Coal Refuse Generated and Used 

(1) Sectors That Generate Coal Refuse:

• Coal Mining Rejects are generated by NAICS industry sector 212111 - 

Bituminous Coal and Lignite Surface Mining, 212112 - Bituminous Coal 

 1 An additional source of coal refuse is coal mill rejects. Mill rejects are produced by coal-fired power 

stations that use roller mills to generate coal mill rejects. These rejects are the dense material in fuel coal that cannot 

be ground by the mills at a power plant to the desired size for burning in the boilers (EPA, 2008). Mill rejects appear 

to have limited fuel value. In a 1995 pilot test, when compared to clean coal the sulfur content of mill rejects 

increased from 1.43 percent to 6.1 percent, and ash content increased from 9.4 percent to 80.3 percent. The heating 

value of the original coal was 13,206 Btu/lb compared to that of the mill rejects of 1,931 Btu/lb (EPRI, 1998, p. 4-8). 

Most mill rejects are co-managed with coal combustion byproducts (CCBs) in landfills or impoundments. A 1996 

EPRI survey of coal-fired power plants found that 55 percent of the 264 sites included in the survey co-managed 

mill rejects with CCBs in landfills or impoundments. An additional limited survey of 24 utilities representing 40 

power plants for this project found that 75 percent of these plants co-managed mill rejects in landfills or 

impoundments. Mill rejects typically represent 0.003 to 0.005 percent of the total ash produced (EPRI, 1998, p.iv). 

As mill rejects appear to have limited fuel value, are typically landfilled, and are a relatively smaller waste stream, 

they were excluded from this analysis. 
Coal Refuse 

2 

Underground Mining, and 212113 - Anthracite Mining. The U.S. Department of 

Energy categorizes the locations of these industries into three regions: 

o Appalachian Region, which includes the states of Alabama, Kentucky 

(eastern), Maryland, Ohio, Pennsylvania, Tennessee, Virginia, and West 

Virginia; 

o Interior Region, which includes the states of Arkansas, Illinois, Indiana, 

Kansas, Kentucky (western), Louisiana, Mississippi, Missouri, Oklahoma, and 

Texas; and 

o Western Region, which includes the states of Alaska, Arizona, Colorado, 

Montana, New Mexico, North Dakota, Utah, Washington, and Wyoming 

(USDOE 2007b, p.14). 

(2) Quantities and Prices of Coal Refuse Generated: 

One estimate reports that, annually, coal mines in the U.S. generate 109 million 

metric tons (120 million short tons) of coal refuse from 600 coal preparation plants in 

21 coal-producing states (TFHRC post-1994, p.1). 

A second estimate can be derived from other knowledge of coal production. In 2007 

the amount of coal produced at U.S. coal mines reached an all-time high of 1,145.0 

million short tons; this production data includes quantities extracted from surface and 

underground mines, and normally excludes secondary materials removed at mines or 

associated preparation plants (USDOE 2007a).2

 Thus, the amount of raw mining 

product is higher than this 1,145.0 million short ton total. The amount of mining 

reject resulting from this production is uncertain, but up to 50 percent of the raw 

mined product may end up as refuse depending on the rock and impurities in the coal 

(VCE 1996). This 50 percent estimate is most applicable where coal is mined from 

longwall mines or otherwise has relatively high rock, impurities, and partings content 

(VEC 1996, p.1). Treating this 50 percent value as an upper bound, no more than 

1,145 million short tons of coal reject were likely to have been generated in 2007 

(i.e., 50 percent of raw mined product is saleable product, while 50 percent is rejects). 

As an example of specific data from one state, fifteen million tons of mining reject 

are generated annually in Virginia (VCE 1996). Another estimate found that, since 

the 18th century, the refuse rate of coal was about 40 percent of the volume of coal 

mined in the U.S. (Neufeld p. 1). However, the same source cites that current coal 

preparation plants are more efficient, producing less coal waste, resulting in a refuse 

rate of about 25 percent in the 1990s. 

Public comments submitted to EPA by the Council of Industrial Boiler Owners 

(CIBO) in response to the Advanced Notice of Proposed Rulemaking (ANPRM) 

indicate that approximately 1.1 billion tons of waste coal are located throughout the 

United States. CIBO reports that this material has an energy equivalency of more 

than 2 billion barrels of oil (assuming an average Btu value of 5,500 Btu per pound 

for the waste coal) (Bessette 2009). 

 2

 This amount does not include the recovery of coal refuse, which was 0.8 million short tons in 2007. 
Coal Refuse 

3 

The combustor survey database developed by EPA for the 2009 proposal of the 

Commercial and Industrial Solid Waste Incinerator (CISWI) standards and the 

Industrial Boilers Maximum Achievable Control Technology (MACT) standards 

includes one source that reported burning approximately 308,000 tons of coal refuse 

per year (EPA 2009).3

Information on the price of coal refuse is limited, but can be expected to compare 

favorably with “virgin” energy sources in the applications where it is used. 

(3) Trends in Generation of Coal Refuse: 

Generation of coal refuse correlates with the production and use of coal. According 

to the DOE’s Annual Energy Outlook 2007 with Projections to 2030, coal production 

is projected to increase in coming decades, particularly in the Powder River Basin of 

Wyoming. From 2005 to 2030, production in the Powder River Basin is projected to 

grow by 289 million tons. The Rocky Mountain, Central West, and East North 

Central regions are projected to show the largest increases in coal demand, by about 

100 million tons each, from 2005 to 2030. Increasing coal use for electricity 

generation at existing plants and construction of a few new coal-fired plants lead to 

forecasted annual production increases that average 1.1 percent per year from 2005 to 

2015. The forecasted growth in coal production is stronger from 2015 to 2030, 

averaging 1.8 percent per year, as new coal-fired generating capacity is added and 

several coal-to-liquids (CTL) plants are brought on line (USDOE 2007b). Overall, 

the generation of coal refuse will likely increase as the demand for coal-based energy 

grows; however, it is unclear how this increase will affect recapturing of existing coal 

refuse from stockpiles. 

3. Uses of Coal Refuse 

(1) Combustion Uses of Coal Refuse: 

• There are 18 coal refuse plants (Fossil fuel electric power generation - NAICS 

221112), and 13 more that use it as a secondary fuel, with bituminous coal as their 

primary fuel. Fourteen of the 18 coal refuse plants are in Pennsylvania, three are 

in West Virginia, and one is in Utah. Seventeen more plants have been proposed 

in Pennsylvania, West Virginia, Kentucky, Indiana, Illinois, Colorado, and 

Virginia (Energy Justice 2007, p.1). 

• According to the Anthracite Region Independent Power Producers Association 

(ARIPPA), from 1988 to the end of 2003, coal refuse plants in Pennsylvania used 

88.5 million tons of coal refuse, mostly from “legacy” refuse piles. ARIPPA’s 

records show that the plants in the Commonwealth burn an average of about 7.5 

million tons of coal refuse per year as fuel, mostly from “legacy” coal refuse piles 

(PADEP 2004a, p.2). 3

 Although we report coal refuse quantities from the database in tons, the database includes material 

quantities expressed in terms of heating values (Btu). To express this information as a tonnage, we assumed that 

coal refuse has a heating value of 7,750 Btu per pound, which is the midpoint of the 6,000 to 9,500 Btu per pound 

range reported by the National Research Council (NRC 2006). In addition, we suspect that the combustor survey 

database may under count the number of sources burning coal refuse, as such sources may have simply identified 

their fuel source as "coal". 
Coal Refuse 

4 

• The type of process used for the combustion of mining rejects is circulating 

fluidized bed (CFB) combustion (also known as fluidized bed combustor (FBC) 

boiler technology) (Energy Justice 2007, p.1). CFB is an integrated technology for 

reducing sulfur dioxide (SO2) and NOx emissions during the combustion of coal. 

For the CFBs currently in use in all sectors, coal is the primary fuel source, 

followed by biomass and coal refuse. The heat input capacities of all industrial, 

commercial, and institutional (ICI) CFB units generally range from 1.4 to 1,075 

MMBtu/hr. (EPA 2004, p.2-7).

(2) Non-Combustion Uses of Coal Refuse

Granular Base: For non-combustion applications, such as use for embankment 

fill, coal refuse is usually cleaned before use to remove carbonaceous material 

that has been known to spontaneously ignite. It may also be spread in thin, 

compact layers between earth fill to reduce oxygen exposure and therefore reduce 

the possibility of ignition (TFHRC post-1994). Coarse coal refuse can be used as 

aggregate in granular base applications. Proper compaction of coarse coal refuse 

to its maximum dry density is necessary to achieve stability within a pavement 

structure. Fine coal refuse slurry has little or no load carrying capability and is, 

therefore, unsuitable for use as a construction material (TFHRC post-1994, p.1). 

In addition, there has been occasional use of coal refuse in Alabama, Kentucky, 

Virginia, and West Virginia as an alternative material for bases and sub-bases 

(TFHRC post-1994, pp.1-2).4

 

A reference indicating the potential volume of coal refuse employed in noncombustion uses was not identified in the course of the preparation of this paper. 

• Mine Reclamation Projects: Ash leftover from combustion in a CFB boiler is 

alkaline and used for mine reclamation projects. The ash is often hauled back to 

the same gob pile site, where it can be mixed with soils impacted by acid mine 

drainage around abandoned mines to neutralize acidity and immobilize heavy 

metals. The Commonwealth of Pennsylvania has certified CFB ash for beneficial 

use in mining reclamation projects, and the Department of Environmental 

Protection regulates and routinely tests it (WPCAMR post-2001, p.2). Following 

combustion of gob in the CFB boiler, the solids that remain are called ash.5

 

• Stockpile Remediation: Some environmental groups advocate for the remediation 

of coal refuse stockpiles where they stand instead of burning them for fuel. 

Research has shown that beach grass can grow in the coal piles and can rebuild 

organic matter. Restored organic matter allows plant cover and eventually native 

species to take root (Energy Justice p. 2). 

 4

 The Pennsylvania Department of Transportation has rejected anthracite refuse usage as aggregate for base 

and subbase courses because of high percent dissolution losses in the sodium sulfate (soundness test). West Virginia 

is evaluating the use of coal refuse as subbase material (TFHRC, post-1994, p.2). 

5

 CFB Ash can be used for other kinds of reclamation projects. For example, one project will use CFB ash 

injected into the partially flooded underground voids of an abandoned mine to mitigate acid mine drainage that 

currently breaks out on the surface (WPCAMR). 
Coal Refuse 

5 

(3) Quantities of Coal Refuse Stockpiled/Stored6

Comprehensive national data concerning the volume of legacy mining rejects was not 

identified during the course of this review. Before 1977, most mining rejects were 

stockpiled and abandoned since mining companies were not legally responsible for 

cleaning up mining waste. This resulted in thousands of abandoned coal refuse 

stockpiles. Pennsylvania alone has 820 abandoned piles constituting 258 million tons 

of coal refuse in the state (PA DEP 2004b p. 1). According to one source, upwards of 

2.4 billion tons of coal refuse had been abandoned in Pennsylvania by 1977 (ARRIPA 

p.1). In 1977 the Surface Mining Control and Reclamation Act (SMCRA) was 

passed, requiring coal companies to reclaim the sites that they mine. At that time, 

state and federal governments began to clean up the abandoned stockpiles using the 

Abandoned Mine Lands Reclamation Fund established by SMCRA and continue to 

do so today. Many state reclamation projects suggest sending refuse piles to CFB 

plants. According to ARIPPA, from 1987 to the end of 2003, coal refuse plants in 

Pennsylvania consumed 88.5 million tons of the material, mostly from “legacy” 

refuse piles. ARIPPA’s records show that the plants in the Commonwealth burn an 

average of about 7.5 million tons of coal refuse per year, mostly from “legacy” coal 

refuse piles (PADEP 2004a, p.2). In fact, many of the coal refuse plants have 10 to 

15 years of fuel available (WPCAMR post-2001 p. 1). 

Currently, mining rejects are managed on-site by the mining company, while few are 

abandoned. Although CFB boilers burning coal refuse appear to primarily utilize 

volumes from “legacy” stockpiles, coal refuse and selective overburden material from 

active mines are being utilized as fuel as well (Bessett 2009). Having particularly 

valuable refuse makes it more likely that a current generator will send ash to a coal 

refuse plant. Relatively low sulfur content, high energy value, and close proximity to 

the plant make coal refuse more appealing for a CFB (WPCAMR post-2001 p. 1). 

4. Management and Combustion Processes 

(1) Types of Combustion Units: 

The two major technologies used to burn coal are pulverized coal combustion and 

fluidized bed combustion. Of the approximately 600 operating coal-fired power 

plants in the United States, about 160 utilize fluidized bed combustion (Goswami 

2007). Although both technologies can be utilized to combust either normal coal or 

waste coal, fluidized bed boilers are noted for their capability to burn fuels with low 

carbon content. This is a result of the turbulent mixing process that takes place in the 

fluid beds, which creates good heat and mass transfer and allows the burning to take 

place at lower temperatures. Therefore, fluidized bed boilers are capable of 

combusting fuels, such as low-carbon waste coal, that do not have a high enough 

heating value to support combustion at high temperatures (Woodruff 2004). 

(2) Sourcing information: 

Sources of mining rejects include coal refuse or “gob/culm piles.”7

 6

 See the CCP Materials Characterization Paper for further information on CCP landfill volumes. 
Coal Refuse 

6 

(3) Processing Information: 

Coal refuse is regulated similarly to coal as a raw material. A coal refuse handler 

must receive a permit under the Office of Surface Mining and Control and 

Reclamation Act. Coal refuse that is reclaimed for secondary use is also subject to 

oversight by the Mining Safety and Health Administration (Bridgeford p. 4-5). 

Following necessary licensing, the general process is as follows: material is hauled 

from mining areas (i.e., gob and culm piles) to coal-fired power plants, crushed into 

pieces smaller than 1⁄4 inch for fluidized bed boilers or fine particles for pulverized 

coal combustion, and then burned for energy (Woodruff 2004). 

For fluidized bed boilers, crushed limestone is injected into the bottom of the 

combustion chamber along with the fuel, where the calcium carbonate in the 

limestone is converted into calcium oxide. The calcium oxide then reacts with the 

sulfur in the coal refuse, thereby reducing the sulfur oxide emissions. The heavier 

fuel and limestone particles that cannot be retained in the circulating fluidized bed 

drop to the bottom of the chamber. This burned fuel, known as bottom ash, is 

removed from the combustion chamber along with any ash captured at the top, 

which is known as fly ash (PADEP 2004b, Ch 1, pp. 3-4). Ash leftover from CFBs 

may be hauled back to the same gob/culm pile site, where it can be mixed with soils 

around abandoned mines to neutralize acidity and immobilize heavy metals 

(WPCAMR post-2001, p.2). 

 

Due to advances in coal preparation technology over the past century, the processing 

of coal has evolved over time such that materials that would have been considered 

mine rejects in the past are now handled and processed as coal. In the early twentieth 

century, coal preparation involved simple size segregation into lump coal for 

domestic use and intermediate-sized coal for industrial use. Coal fines were 

considered unfit for use and were disposed of as mine rejects in coal refuse piles. 

Today, however, coal preparation plants are much more capable of separating coal 

from mineral matter through processes such as density separation and froth flotation 

(NRC 2007). In the past, mines discarded coal pieces smaller than 0.5 millimeters, 

but technological improvements have allowed the size of rejected fines to decrease to 

those smaller than 0.04 millimeters (Yoon 2009). 

(4) Changes in Technology to Improve Use of Coal Refuse in Combustion: 

As noted, the advent of circulated fluidized bed (CFB) combustion boilers, along with 

higher fuel costs, has facilitated the combustion uses of coal refuse. In addition, 

certain technology advancements are in use or development that may serve to further 

improve the application of coal refuse in combustion: 

 7

 Based on the sources consulted in the development of this document, brokers or traders do not appear to 

be involved in sourcing the waste products to the power plants. It appears the utilities/power plants are supplying 

themselves with the waste pile materials. 
Coal Refuse 

7 

• CSIRO-Liquatech hybrid coal and gas turbine system, developed in Australia, 

harnesses existing technologies in a 1.2 megawatt hybrid coal and gas turbine 

system that burns coal refuse and methane gas to generate electricity. The turbine 

system burns coal and methane in a kiln, producing hot air, which is then driven 

through a heat exchange unit and subsequently passed over a gas turbine to 

produce electricity. The electricity can either be used to power a mine’s 

operations or be returned to the grid for general consumption. (CSIRO 2002, p.1). 

• Radar Acquisitions Corp. is in the process of developing an engineered solid fuel 

(Re-FuelTM) for utilities. The primary component of Re-FuelTM is coal refuse 

(gob piles and coal slurry pond material); the secondary component is biomass 

(i.e., agricultural material or sawdust). The goal of the RPS FuelsTM technology is 

to convert these two materials into a product that looks and acts like coal, but 

burns more efficiently and with reduced stack emissions (Radar, p.1). 

(5) State Status of Combustion as Beneficial Use: 

There are currently three states that have power plants that burn coal refuse as fuel 

(Pennsylvania, West Virginia, and Utah). There are currently five additional states 

that are proposing to build power plants that will burn coal refuse: Kentucky, 

Indiana, Illinois, Colorado, and Virginia.8

 

5. Coal Refuse Composition and Impacts 

(1) Composition of Coal Refuse

The Btu value for this material is 6,000 to 9,500 Btu per pound (NRC, 2006). 

Nationally, this material has an average of 60 percent of the BTU value of normal 

coals (Energy Justice 2007, p.1). The ash content of coal refuse is high: according to 

an ARIPPA-sponsored study, twelve Pennsylvania plants using coal refuse as a key 

ingredient of their fuel, burned over 8 million tons/year of refuse coal and generated 

in the process approximately 5 million tons of ash (Earthtech 2000, Vol. 1, p. iv). 

Similar to coal itself, the chemical composition of coal refuse varies geographically. 

Exhibit 1 presents elemental data from the published literature for coal refuse samples 

extracted from the Peerless Seam in West Virginia (Stewart et al. 2001) and a 

separate seam in southwest Virginia (Li et al. 1997). Based on data submitted by RRI 

Energy in response to the proposed rule, Exhibit 2 presents constituent concentrations 

of coal refuse for samples from Cambria, Indiana and Somerset County, 

Pennsylvania. 

 8

 Note that this information represents the results of preliminary research; we have not performed an 

exhaustive investigation of state activities and regulations for all states concerning coal refuse. 
Coal Refuse 

8 

Exhibit 1: Chemical Properties of Coal Refuse 

from West Virginia and Virginia 

Element ppm 

Ag <5 

Al 91,000 

As <10 

B 200 

C 167,000-190,000 

Ca 23000 

Cd 0-6.4 

Cr 70-83.3 

Cu 26-60 

Fe 30000 

Hg 0.3 

Mg 8000 

Mn 140-1026 

N 2700 

Ni 29.8 

P 160 

Pb 15.8-20 

S 36500 

Si 222000 

Zn 60-112 

Sources: Stewart, et al (2001), Li, et al (1997) 

Mining rejects have a higher concentration of mercury than normal coals. In West 

Virginia and nationally, gob has 4 times more mercury than bituminous coal. In 

Pennsylvania, gob has 3.5 times more mercury than bituminous coal. Culm has 19 

percent more mercury than anthracite coal. Bituminous rejects also have higher 

levels of sulfur. Data on other metals in the material is sparse, but single metals tests 

on Pennsylvania culm and gob show both to have about four times more chromium 

and three times more lead (Energy Justice 2007, p.1), and the content of arsenic is 

relatively elevated as well (Coleman and Bragg, 1990, in Earthtech, 2000, Vol. 1, pp. 

15-16). 

The composition of coal mining rejects is similar for those mined from legacy piles 

and those generated from current mining activities, although the size of the fines 

produced has decreased over the years as a result of technology improvements. 

However, the ash concentrations and contaminant concentrations of coal mining 

rejects depend largely on the type of coal and location of the mine, rather than the 

year in which the rejects were mined (Yoon 2009). 
Coal Refuse 

9 

Exhibit 2: Constituents of Coal Refuse from Indiana and Pennsylvania

Sample 

Description Sample ID Sb As Be Cd Cr Co Pb Mn Hg Ni P Se 

Coal Refuse 

(values in 

ppm) 

Sample 1 1.5 50.7 2.1 0.3 80.2 22.7 33.1 134 0.644 44.7 718 7.8

Sample 2 1.7 53.4 2.1 0.3 84.5 23.8 35.2 139 0.748 50.5 719 8.6

Sample 3 1.5 47.3 2.1 0.3 84.7 22.8 33.1 144 0.613 47.1 745 8.6

Average 1.6 50.5 2.1 0.3 83.1 23.1 33.8 139 0.668 47.4 727 8.3

Source: RRI Energy, Inc. (2010). Values represent constituent concentrations of coal refuse in Cambria, Indiana and 

Somerset County, Pennsylvania. 

(2) Impact Information

As noted, the typical process used for the combustion of mining rejects is circulating 

fluidized bed (CFB) combustion (Energy Justice 2007, p.1). CFB is an integrated 

technology for reducing sulfur dioxide (SO2) and NOx emissions during the 

combustion of coal. In a typical CFB boiler, crushed coal and inert material (sand, 

silica, alumina, or ash) and/or a sorbent (limestone) are maintained in a highly 

turbulent suspended state by the upward flow of primary air from the windbox 

located directly below the combustion floor. This fluidized state provides a large 

amount of surface contact between the air and solid particles, which promotes 

uniform and efficient combustion at lower furnace temperatures than conventional 

coal-fired boilers. The lower combustion temperature is below the threshold at which 

nitrogen and oxygen form NOx and therefore leads to reduced emissions. Once the 

hot gases leave the combustion chamber, they pass through the convective sections of 

the boiler, which are similar or identical to components used in conventional boilers. 

For the CFBs currently in use in all sectors, coal is the primary fuel source, followed 

in descending order by biomass, coal refuse, and municipal waste. The heat input 

capacities of all ICI CFB units generally range from 1.4 to 1,075 MMBtu/hr (EPA 

2004, pp.2-7). 

Concerning impacts related to emissions from this combustion process, the 

Pennsylvania Department of Environmental Protection (PADEP) required the owners 

of a Pennsylvania bituminous coal refuse fired facility to conduct extensive air toxics 

emissions stack testing to support its request to burn a 10 percent mixture of coal tar 

contaminated soil in combination with normal coal refuse. The coal refuse facility 

shows lower emissions for all of the toxic pollutants compared to a typical pulverized 

coal combustor. The dioxin levels were approximately 4 times lower, while most 

metals were about half, with the exception of mercury, which was 10 times lower per 

gigawatt-hour generated (PADEP post-2004, p.2). Based on stack testing of two CFB 

combustion plants, 99.7% to 99.8% of the mercury was captured in the ash 

(Earthtech, 2000, Vol. 1, p. vi). According to the same source (Earthtech, 2000, 
Coal Refuse 

10 

Vol.1, p. 1), there are several reasons for the general low emission levels of trace 

metals such as As, Cd, Cr, Hg, Pb, Ni and Se in the fluidized bed combustion process. 

Those include the significantly lower combustion temperatures (800-950 0

C) as 

compared to pulverized coal combustion boilers (1200-1540 0

C), Lower combustion 

temperatures allow mercury to condense as it is exhausted and therefore is more 

likely captured by emissions control devices downstream (Las Brisas Energy Center 

p. 1). The presence of a fabric filter baghouse (FF) also decreases mercury emissions 

in both CFB and PC units. Units with a FF produce fly ash with both a larger surface 

area and larger pore volume, and therefore allows for more complete fixation of 

mercury and lower emissions. The relative amount of mercury emitted can also 

depend on the type of coal burned (Yan et al. 2008). 

The culm (reject anthracite coal) combusting facilities represent the majority of the 

coal refuse facilities in Pennsylvania and the data submitted to the Department shows 

that these facilities have been achieving a NOx emissions level of 0.15 lbs/MMBtu. 

In comparison, a typical pulverized coal facility without add-on selective catalytic 

reduction (SCR) controls, which is presently the majority of pulverized units, would 

emit NOx in the 0.3 to 0.5 lb/MMBtu range. This continuous emissions monitoring 

(CEM) data also shows that some of the coal refuse facilities have been achieving an 

SO2 emissions rate of 0.20 to 0.25 lbs/MMBtu range using limestone injection. The 

pulverized coal-fired boilers typically emit in the range of 2 to 3 lbs. of SO2 per 

MMBtu. The six Pennsylvania pulverized coal-fired units with SO2 scrubbing operate 

in the 0.1 to 0.4 lbs. of SO2 per MMBtu range (PADEP post-2004, p.2). 

Pennsylvania coal refuse burning facilities are lower emitters of both NOx and SOx 

than the typical coal-fired utilities. However, it should also be noted that an SO2

emission rate of 0.1 lbs/MMBtu is achievable for a newly built pulverized coal-fired 

unit that would be required to install an SO2 scrubber under an SO2 Best Available 

Control Technology (BACT) determination. Therefore, newly constructed electric 

generating combustors of either coal refuse or coal would emit at very comparable 

levels, because both would be employing very similar BACT for all pollutants. 

(PADEP post-2004, p.2). 

Impacts related to the use of coal refuse are discussed qualitatively below. Note that 

a further discussion of the uses of coal combustion products (CCPs) as ingredients is 

provided in the CCP Materials Characterization Paper. 

• Other Impacts Related to Mining Rejects: 

The potential benefits of returning suitable FBC ash to abandoned or active mine 

lands for use in reclamation include: 

o The alkaline nature and encapsulating ability of the material make it useful for 

some mine reclamation applications. In particular, reclaiming coal refuse 

piles without the benefit of adding FBC ash does less to address the oftensevere water quality problems that emanate from some of the piles. 
Coal Refuse 

11 

o The reclamation of abandoned mine land (AML) with FBC ash is often 

privately funded, freeing up state and federal government AML resources for 

other applications. 

o The ash from FBC plants has chemical and physical properties that limit the 

potential for the ash itself to become a source of environmental contamination 

(Earthtech, 2000, Vol 1, pp. v-vi; PADEP 2004b, Ch. 1, pp.6-7). 

o Reclaiming AML with ash serves to eliminate the safety hazard of abandoned 

mine highwalls and cropfalls. 

In addition, as indicated in public comments submitted to EPA in response to the 

ANPRM, the use of coal refuse as a fuel results in environmental benefits 

associated with (1) reducing abandoned mining waste piles, which threaten 

groundwater and air quality (through windblown fugitive emissions), and (2) 

reclaiming abandoned mine sites, thereby returning lands to productive use 

(Bessette 2009). According to public comments, coal waste piles that are not 

removed generally create severe acid mine drainage, with pH levels of 

approximately 2.5. Elevated concentrations of metals, including arsenic, occur at 

these sites, as well. Legacy coal refuse piles in Pennsylvania, those refuse piles 

that were a result of coal mined prior to Pennsylvania receiving primacy on July 

31 , 1982, include more than 220 million tons of refuse and cover more than 8,500 

acres. Since 1990. 78 million tons of coal refuse have been mined for fuel in the 

Anthracite Region and 35 million tons of coal waste have been mined in the 

Bituminous Coal Region of Pennsylvania (Brady 2010). 

• Additional Avoided Impacts: 

Exhibit 4 summarizes the air emissions associated with the combustion of coal 

refuse and the corresponding emissions from the combustion of coal. The exhibit 

also presents the cradle-to-gate emissions that may be avoided by using coal 

refuse as a substitute for coal. These cradle-to-gate environmental benefits may 

be offset by the environmental impacts associated with extracting coal refuse 

from coal refuse piles and processing this material, but data are not readily 

available on these impacts. Note that there may be alternative uses (e.g., 

aggregate, mine reclamation) that are environmentally preferable to combustion. 

Furthermore, use of coal refuse as a fuel serves the important benefit of removing 

the piles of gob and culm. The piles can be a fire hazard and a source of surface 

and ground-water pollution. 
Coal Refuse 

12 

Exhibit 4: Emissions from Combustion of Coal Refuse and Extraction and Combustion of 

Traditional Coal 

Pollutant 

Coal Refuse Coal 

Combustion Combustion 

Combustion plus 

Upstream 

---------- Lb./MMBtu ----------

Criteria Pollutants 

PM2.5 - - - 

PM10 - 0.054 0.054 

PM, unspecified - - 0.246 

NOx 0.15 0.482 0.504 

VOCs - 0.006 0.014 

SOx 0.20 - 0.25 1.446 1.469 

CO - 0.068 0.085 

Pb - 8.93x10-6 9.19x10-6

Hg - 2.05x10-6 2.14x10-6

Greenhouse Gases 

CO2 - 210.7 214.7

CH4 - 0.007 0.458

N2O - 0.003 0.003

MTCO2E/MMBtu - 0.096 0.102

Sources:

PADEP post-2004, p.2; Franklin Associates 1998. 

Note:

“-” signifies data not available; may equal zero. 

The emission information presented in this table is derived from Life Cycle Inventory 

(LCI) data, as compiled by Franklin Associates. LCI data identifies and quantifies 

resource inputs, energy requirements, and releases to the air, water, and land for each step 

in the manufacture of a product or process, from the extraction of the raw materials to 

ultimate disposal. The LCI can be used to identify those system components or life cycle 

steps that are the main contributors to environmental burdens such as energy use, solid 

waste, and atmospheric and waterborne emissions. Uncertainty in an LCI is due to the 

cumulative effects of input uncertainties and data variability. 

There are several life cycle inventory databases available in the U.S. and Europe. For this 

paper, we applied the most readily available LCI database that was most consistent with 

the materials and uses examined. These LCI data rely on system boundaries as defined by 

Franklin Associates, as described in the documentation for this database, available at: 

http://www.pre.nl/download/manuals/DatabaseManualFranklinUS98.pdf. 
Coal Refuse 

13 

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